However, saying that, my experience has proved different. Some years ago I installed a very thick safety film onto my car windows. The film thickness was 300 micron which is known in the industry as a triple layer. Some window film companies refer to it as “bullet resistant” window film as it definitely slows down the force of a bullet.
Immediately after the installation drivers notice a huge difference as the traffic noise was reduced to a pleasant level and this changed the driving experience. So yes, film on glass most certainly does reduce the noise factor.
The level of noise inside a building will depend on the nature of the glazing material, the layout of the room, the thickness of the walls and the amount of furniture in the room. The glass thickness plays an important roll in the insulating properties of a building when it comes to noise.
Double glazing is very popular for noise reduction and the application of thick safety film on both sides of the glass will improve the performance. When double glazing is installed one should have a gap between the layer of glass. the glass needs to be sealed properly and the air also helps deaden the noise. The larger the gap the better the performance.
The higher one goes up in a building the sound will decrease and the larger the window area is the more the noise will be noticed.